func (i *inputBytes) Context(pos int) syntax.EmptyOp {
r1, r2 := endOfText, endOfText
if pos > 0 && pos <= len(i.str) {
r1, _ = utf8.DecodeLastRune(i.str[:pos])
}
if pos < len(i.str) {
r2, _ = utf8.DecodeRune(i.str[pos:])
}
return syntax.EmptyOpContext(r1, r2)
}
// As I understand it this thing should check the rune before and the one
// after the given location? IS THIS THING EVER USED?!
func (i *inputReadSeeker) Context(pos int) syntax.EmptyOp {
pos = pos + i.start
//log.Println("Context: ", pos)
//log.Println(pos)
ol, _ := i.r.Seek(0, 1)
defer i.r.Seek(ol, 0)
r1, r2 := endOfText, endOfText
if len(i.buf) != 8 {
if cap(i.buf) < 8 {
i.buf = make([]byte, 8)
} else {
// TODO: Is this how to extend a slice to its maximum capacity?
i.buf = i.buf[:8]
}
}
// Try to read out the surrounding 8 bytes but take care so that
// if we are to early we read fewer before
posa := pos - 4
if pos < 4 {
posa = 0
}
_, e := i.r.Seek(int64(posa), 0)
if e != nil {
return syntax.EmptyOpContext(r1, r2)
}
n, e := i.r.Read(i.buf)
if pos > 0 && n > 0 {
r1, _ = utf8.DecodeLastRune(i.buf[:pos-posa])
}
if n > pos-posa {
r2, _ = utf8.DecodeRune(i.buf[pos-posa:])
}
return syntax.EmptyOpContext(r1, r2)
}
func (f *File) Context(pos int) syntax.EmptyOp {
pos += f.pos
r1, r2 := endOfText, endOfText
if pos > 0 && pos <= f.Length() {
if pos < f.gapStart {
r1, _ = utf8.DecodeLastRune(f.b[:pos])
} else {
r1, _ = utf8.DecodeLastRune(f.b[:pos+(f.gapEnd-f.gapStart)])
}
}
if pos < f.Length() {
if pos < f.gapStart {
r2, _ = utf8.DecodeRune(f.b[pos:])
} else {
r2, _ = utf8.DecodeRune(f.b[pos+(f.gapEnd-f.gapStart):])
}
}
return syntax.EmptyOpContext(r1, r2)
}
// match runs the machine over the input starting at pos.
// It reports whether a match was found.
// If so, m.matchcap holds the submatch information.
func (m *machine) match(i Input, pos int) bool {
startCond := m.re.cond
if startCond == ^syntax.EmptyOp(0) { // impossible
return false
}
m.matched = false
for i := range m.matchcap {
m.matchcap[i] = -1
}
runq, nextq := &m.q0, &m.q1
r, r1 := endOfText, endOfText
width, width1 := 0, 0
r, width = i.Step(pos)
if r != endOfText {
r1, width1 = i.Step(pos + width)
}
var flag syntax.EmptyOp
if pos == 0 {
flag = syntax.EmptyOpContext(-1, r)
} else {
flag = i.Context(pos)
}
for {
if len(runq.dense) == 0 {
if startCond&syntax.EmptyBeginText != 0 && pos != 0 {
// Anchored match, past beginning of text.
break
}
if m.matched {
// Have match; finished exploring alternatives.
break
}
if len(m.re.prefix) > 0 && r1 != m.re.prefixRune && i.CanCheckPrefix() {
// Match requires literal prefix; fast search for it.
advance := i.Index(m.re, pos)
if advance < 0 {
break
}
pos += advance
r, width = i.Step(pos)
r1, width1 = i.Step(pos + width)
}
}
if !m.matched {
if len(m.matchcap) > 0 {
m.matchcap[0] = pos
}
m.add(runq, uint32(m.p.Start), pos, m.matchcap, flag, nil)
}
flag = syntax.EmptyOpContext(r, r1)
m.step(runq, nextq, pos, pos+width, r, flag)
if width == 0 {
break
}
if len(m.matchcap) == 0 && m.matched {
// Found a match and not paying attention
// to where it is, so any match will do.
break
}
pos += width
r, width = r1, width1
if r != endOfText {
r1, width1 = i.Step(pos + width)
}
runq, nextq = nextq, runq
}
m.clear(nextq)
return m.matched
}
